Convective response to changes in the 1 thermodynamic environment in idealized weak 2 temperature gradient simulations

We investigate the response of convection to idealized pertur-4 bations in the thermodynamic environment in simulations which parame-5 terize the large scale circulations using the weak temperature gradient (WTG) 6 approximation. The perturbations include a combination of modifying the 7 environmental moisture and atmospheric stability via imposing anomalies 8 in reference moisture and temperature profiles. We find that changes in at-9 mospheric stability strongly influence the character of convection by dras-10 tically modifying the vertical motion profile, whereas changes to atmospheric 11 moisture modulate the intensity of precipitation produced by the convection, 12 but do not qualitatively change the shape of the vertical motion profile. 13 An important question is how does horizontal moisture advection into the 14 domain affect convection? We test several different parameterizations of this 15 process; these include lateral entrainment by circulations induced by enforc-16 ing WTG, a moisture relaxation which parameterizes the advection of mois-17 ture by large scale non-divergent circulations, and control simulations in which 18 both of these mechanisms are turned off so horizontal advection is assumed 19 negligible compared to vertical advection. Interestingly, the most significant 20 differences resulting from the choice of horizontal moisture advection scheme 21 appear in environmental conditions which suppress–rather than support–the 22 development of deep tropical convection. In this case, lateral entrainment re-23 lated to WTG circulations is the only parameterization which results in ex-24 treme drying of the troposphere in environments which suppress convection.